Force sensing in a distal region of an instrument including single-core or multi-core optical fiber

Patent metadata

Field	Value
Publication number	US-11313674-B2
Application number	US-202017115694-A
Country	US
Kind code	B2
Filing date	Dec 8, 2020
Priority date	May 15, 2015
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

An optical force sensor along with an optical processing apparatus and method are disclosed. The optical force sensor includes an optical fiber, a core included in the optical fiber, an instrument including the optical fiber, the instrument having a distal region, and a tubular structure encasing an end of the optical fiber and secured to the first conduit at the distal region of the instrument. When an optical interferometric system is coupled to the optical fiber, it processes reflected light from a portion of the core included within the tubular structure that does not include Bragg gratings to produce a measurement of a force present at the distal region of the instrument.

First claim

The invention claimed is:

1. An optical force sensor, comprising:
an optical fiber comprising one or more optical cores surrounded by a cladding, the optical fiber being terminated in a distal region to suppress back reflection, the optical fiber comprising a Bragg grating along the one or more optical cores except in the distal region; and
a protective tube encasing the distal region of the fiber, filled with an epoxy that transfers strain from the protective tube to the optical fiber.

2. The optical force sensor of claim 1 , wherein the epoxy is index-matched to the optical fiber.

3. The optical force sensor of claim 1 , wherein the protective tube is made of at least one of glass, polymer, or metal.

4. The optical force sensor of claim 1 , wherein the optical fiber is terminated in the distal region by angle cleaving or tapering.

5. The optical force sensor of claim 1 , further comprising a coating surrounding the cladding except in the distal region.

6. The optical force sensor of claim 5 , further comprising a conduit containing the optical fiber.

7. The optical force sensor of claim 6 , wherein the protective tube is secured to the conduit in a bonded region at a distal end of the conduit by mechanical attachment.

8. The optical force sensor of claim 6 , wherein the protective tube is secured to the conduit in a bonded region at a distal end of the conduit by adhesive attachment or flame spray attachment.

9. The optical force sensor of claim 8 , wherein the conduit is bonded to the protective tube in a bonded region extending as far as the protective tube.

10. The optical force sensor of claim 8 , wherein the conduit is bonded to the protective tube and the coating in an extended bonded region.

11. The optical force sensor of claim 8 , wherein the one or more optical cores comprise multiple optical cores.

12. An optical fiber force sensing system comprising:
an optical force sensor comprising:
an optical fiber comprising one or more optical cores surrounded by a cladding, the optical fiber being terminated in a distal region to suppress back reflection, and
a protective tube encasing the distal region of the fiber, filled with an epoxy that transfers strain from the protective tube to the optical fiber; and

an optical interferometric system coupled to the optical fiber and configured to process light Rayleigh-backscattered along the one or more cores in the distal region of the optical fiber to produce a measurement of strain due to a force present at the protective tube.

13. The system of claim 12 , wherein the optical fiber comprises a Bragg grating along the one or more cores except in the distal region.

14. The system of claim 12 , wherein the optical interferometric system is further configured to process light reflected off the Bragg gratings to produce a measurement of strain along the one or more optical cores.

15. The system of claim 12 , wherein the optical fiber comprises multiple optical cores and the optical interferometric system comprises a multi-channel optical interrogator coupled to the multiple optical cores and configured to process light Rayleigh-backscattered along the multiple optical cores in the distal region to produce measurements of strain due to a force present at the protective tube for the multiple optical cores and to distinguish between strains due to bending and axial strains based on the multiple determined strains.

16. The system of claim 15 , wherein fiber lengths in the multi-channel optical interrogator differ between different interferometric paths associated with different respective cores of the multiple optical cores.

17. A method for measuring forces with an optical force sensor comprising an optical fiber terminated in a distal region to suppress back reflection and an epoxy-filled protective tube encasing the distal region, the method comprising:
using an optical interferometric system coupled to the optical fiber to measure a phase signal of light Rayleigh-backscattered along one or more cores of the optical fiber in the distal region of the optical fiber; and
processing the phase signal to determine a strain due to a force on the protective tube, transferred from the protective tube to the optical fiber via epoxy filling the protective tube.

18. The method of claim 17 , wherein the optical fiber comprises multiple cores and wherein phase signals of light Rayleigh-backscattered in the distal region are measured and processed for the multiple cores to determine strains due to a force on the protective tube for the multiple cores.

19. The method of claim 18 , the method further comprising distinguishing between strains due to bending and axial strains based on the multiple determined strains.

20. The method of claim 18 , wherein the phase signals are measured with at least one of the multiple cores being offset in interferometric path length from other ones of the multiple cores to prevent signal mixing within the protective tube.

Assignees

• Intuitive Surgical Operations

Inventors

• Gifford Dawn K
• Barbagli Federico
• Chang Samuel
• Kowshik Anoop B
• Wagner Oliver
• Paris Michael
• Froggatt Mark E

Classifications

• G01L1/24 Primary

  by measuring variations of optical properties of material when it is stressed, e.g. by photoelastic stress analysis {using infrared, visible light, ultraviolet} · CPC title

• G02B23/26

  using light guides {(for illumination G02B23/2469)} · CPC title

• G02B6/34

  utilising prism or grating {(G02B6/293 takes precedence)} · CPC title

• G02B6/022

  using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper (G02B6/02204 takes precedence; optical modulation using photo-elastic effect G02F1/0131) · CPC title

• A61B1/00096

  Optical elements · CPC title